Ball-lapping machine



A. F. ROCKWELL.

BALL LAPPING MACHINE. APPLI CATION\ FILED MAR. 19, 19w. 1,419,078, PatentedJune 6, 1922 4 SHEETSSHEET FIG] IN V EN TOR.

A TTOR NE Y.

A. F. ROCKWELL.

BALL LAPPING MACHINE. APPLICATION FILED MAR. 19, 1919.

Patefited June 6, 1922.

'4 SHEETS-SHEET 2.

INVENTOR y -QM A TTORNEY.

A. F. ROCKWELL. BALL LAPPING MACHINE. APPLICATION FILED MAR-19,1919- 'Patented June 6, 1922.

4 SHEETS-SHEET 3.

$2M n v A TTOR NE Y.

QFI

A. F. ROCKWELL.

BALL LAPPING MACHINE. APPLICATION FILED MAR. l9 1919.

1,419,078; t d u 6, 1922.

4 SHEETS-SHEET 4.

I v I A TTORNE Y STATED? if @FFEQEL ALBERT F. ROCKWELL, OF BRISTOL, CONNECTICUT, ASSIGNOR, BY ASSIGIN- MEETS, TO STANDARD STEEL AND BEARINGS INCORPORATED, OF VTLELMINGTDN, DELAWARE, A CORPORATION OF DELAWARE.

BALL-LAPPING MACHINE.

xiare,are.

Specification of Letters Patent. Patented Jung 6 1922 Application filed March 19, 1919. Serial No. 283,622.

To (all whom it may co nccw'zh Be it known that I, ALBERT F. "looKwELL,

a citizen of the United States, residing at Bristol, in the county f Hartford and State of Connecticut, have invented certain new and useful Improvements in Ball-Lapping Machines, of whichthe following is a specification.

This invention relates to ball-lapping devices for use in the manufacture of ballbearings, and provides an apparatus in which a greatly increased. production, efficiency of operation, and improved quality of product is obtained over results possible to be secured by devices of this general'nature duced to the required size. Upon a careful analysis, it will be clear that in a construction such as this, in which the balls must pass more than once through the same groove, the individual grooves will. be repeatedly traversed by balls of diminishing size. This is objectionable 111 general for the reason that the best grinding conditions are attained only when there is a definite and constant size relation existing between the grooves in the lapping members and the balls undergoing the lapping operation, and such conditions cannot be had when the same balls are caused to travel repeatedly through the same grooves a great number of times, as has heretofore been the ractice.

\Vith the end in view of providing a lapping machine in which each one of the lapping grooves acts on approximately only the same size of balls, as against the previouslyknown methods of ball production in which repeated operations were performed by the same grooves on balls differing 111 size, as a result of their traveling over and over again through the same groove, I have succeeded in producing anapparatus in which a bank or series of sets of lapping plates is provided, and I preferably provide a sufficient number of the lapping-device units to obviate the necessity for causing the balls to travel through the grooves more than once, thereby establishing a definite and constant size relation between the grooves and the balls passing therethrough, whereby the most efiicient operating conditions are attained. However, I do not hold myself rigidly to this particular mode of operation, but may repeat the travel of the balls throughthe grooves under certain circumstances, without departing from the spirit of my invention, although I donot consider this to be the most desirable practice; In order to carry out my invention, I preferably form the successive series of lapping grooves either in a gradually decreasing size or in condition to readily assume such size in use so as to conform with the minute changes in size that the balls undergo in passing from groove to groove in their travel from the entrance to the exit end of the machine, and I provide structure whereby the form of all the grooves will be of substantially the same radius of curvature as that of the balls passing therethrou'gh,to thereby'apply the grinding action simultaneously to substantially every portion of the spherical surface of the balls.

I not only provide a bank or series ofsets of lapping plates, but I also contemplate the making of changes in the number of lapping sets or units employed. in any given operation, in accordance with the particular reqi'lireinents of different classes of work. This flexibility in the capacity of the n achine by which it may be adapted to'opcrate on a batch of ball members requin ingacomparatively small amount of lapping action, or by which the number of lapping units employed can be extended to suit the requirements of a batch in need'of a more extended operation, is a useful and important feature of the invention.

To provide for the application of a suiticient pressure on the balls as well as to still further insure that substantially the entire surface of the balls willbe acted upon I provide for the actual contact with each other in operation of the oppositely-diswidth to cause them to be worn down at a somewhat faster rate than the rate of wear of the grooves, to thereby insure at all a device in which the abrasive material is constantly stirred while the machine is in operation without the use of supplementary stirring apparatus, such asis used in prlor devices, and, in addition, an extremely regular and uniform application of the abrasive material to the lapping grooves is effected, in contrast to the irregular application which was secured in prior devices witha resulting lack of uniformity and efficiency n the lapping operation.

Still another feature of the invention resides in a simple and effective form of transfer mechanism whichI have provided for transferring the balls successively from one groove to another, and preferably from one face to the other of the stationary plates in alternation, at the completion of travel of the balls through each successive groove. I also provide means for automatically transferring the balls from one set of lapplng members to the next to thereby cause the balls to traverse in turn the entire series of sets of lapping members contained in the machine.

Means are also provided for exerting a substantial lateral pressure on the plates in order to hold them in the most effective op-- erating relation to the interposed balls and to do this without-exertin an objectionable end thrust on the shaft. l accomplish this by causing the thrust forces acting longitudinally of the drive-shaft to be mutually balanced and self-contained between the ends of the shaft, so that no end thrust is exerted on the shaft bearings and conse quently no thrust bearing for theshaft is required. This has been accomplished by mounting both the stationary and the rotatable plates on the shaft in such a way that they are movable along the shaft and confined, together with a powerful spring which is used to hold the plates in close contact, between suitable collars mounted on the shaft, one of which has a fixed relation thereto, and the other of which has an adjustable relation therewith. V

In general, it is the object of the invention to provide an apparatus for. performing the lapping operation on the balls in a continuous operation that not only secures a greatly increased production of finished balls over the production secured by lapping machines known and used in the prior art, but also turns out a more regular and uniform product and saves wear upon the lapping ma chine in several important respects.

In the drawings in which a preferred embodiment of the inventions is illustrated,-- Fig. l is a vertical, longitudinal section of a balldapping machine embodying the invention;

Fig. 2 is an end elevation of the machine shown in Fig. 1 looking from the left;

F ig. 3 is a face view of one of the stationary lapping members;

Fig. 4: is an edge view of av portion of the lapping plate shown in Fig. 3; p i

F ig. 5 is an enlarged view of a portion of a ball transfer member forming part of' the transfer mechanism shown in Figs. 3 and 4;

Fig. 6 is a diagrammatic view'on an enlarged scale of a detail of a ball-transfer device used in the machine; and

Fig. 7 is a diagrammatic view showing the course of travel of the balls inthe lapping and transfer operations.

In the drawings, I have shown a balllapping machine in which a bank or series of alternately arranged stationary lapping plates 1 and 2., and. rotatable lapping plates 3 and l, are mounted on the horizontal main drive-shaft 5 which is journaled in bearings 6 and 7 on the end plates 8 of the vat or trough-shaped framework of the machine and is provided with suitable fixed and loose drive pulleys 17 and 18. The contiguous faces of the lapping discs or plates are provided with a series of concentric grooves 9 in their faces through which the balls being operated upon are caused to travel by the rotation of the rotatable plates. In the operation of the device,mcans are provided for transferring the balls at the completion of thetravel about the annular path afforded by any given groove on one face of a fixed plate through the plate to the oppositelydisposed groove on the opposite face thereof, and for re-transferring the balls through the plate when their travel through the lat ter groove is completed, and at the same time I for shifting them radially outward to the next pair of concentric grooves in the series. This operation of causing the balls to travel in succession through each pair of oppositely-disposed grooves is continued until all the grooves from the innermost to the outermost groove in any given set of lapping plates has been traversed, when the balls are automatically transferred to a new series of grooves occupying the contiguous faces of the nextset of, plates, when a similar course of action is proceeded with, and a repetition of the operation described,-that is, the progressive workingof the balls outwardly through each oppositely disposed pair of grooves from the innermost to the outermost I main drive-shaft 5.

are initially and continuously fed into one end of the machine from a hopper 10, and a corresponding number of finished balls is continuously delivered at the other, so that there is no necessary interruption or stop- I page of the machine, under normal operating conditions, while a supply of balls is available in the hopper.

In order to initiate the travel of the balls into the apparatus to undergo the lapping operation, the hopper 10 is arranged to be rotated, and for this purpose the-hopper is provided with a vertical drive shaft 11 journaled in a bearing 12 mounted on the hopper supporting base member 18. The hopper drive-shaft 11 is preferably driven through a gear connection with the counter-shaft 14: which carries a pulley 15 from which a beltdriving connection may be had with a pulley 16 carried by the corresponding end of the It will be seen that the agitation of the balls brought about by the rotation of the hopper 10 will insure the feeding of a continuous succession of balls into the stretch of flexible metallic tubing 19, which leads to the first fixed plate-carrying discs 20 in the series of sets of lapping devices. v

For the purpose of producing relative r0- tative motion between contiguous lapping plates, the stationary plate carrying discs 20 are constructed with central openings 21 within which the drive-shaft 5 can freely turn, and, to prevent rotation of the discs 20,

each one of them is provided with stop member taking the form of a bolt 22 which is fitted into a notch 23 in the periphery of the disc and which bears against the upper edge of the framework of the machine, thus holding the disc and the grooved plates 1 and 2 carried thereby against rotation. The rotatable plate-supporting members or discs 24 and 25 which alternate with the stationary discs 20, instead of being constructed to permit of the free rotation of the discs, are provided with key members 26 which engage with a groove 27 extending longitudinally of the shaft. It will be seen that by the construction described the plate-carrying members 2 1 and 25 are caused to rotate with the drive-shaft 5, and that both the rotatable plate-carrying members 24 and 25 and the stationary plate-carrying discs 20 are capable of movement longitudinally of the shaft, a feature which is utilized in bringing about and maintaining an effective operating pressure on the balls interposed between the plates, as will be hereinafter described.

After passing through the feeding tube 19 from the hopper 10, the balls are directed by means of a passage 62, located in the first stationary plate-supporting disc 20, to a suitable transferring device by means of which the balls are transferred alternately from one face to the other of the stationary lapping member, and in succession from the innermost to the outermost of the series of lapping grooves 9 in the set. Upon emerging from the final groove, the balls are directed byv means of another flexible feeding tube, such as is shown at 28, to the passage corresponding to 62 in the stationary plate-supporting disc 20 of the second set, whereupon the balls traversein turn all the lapping grooves of that set from the innermost to the outermost grooves, and are then transferred to the next set of lapping members, and so on. It will be seen that by this general construction the balls traverse in succession all of the lapping grooves in the entire series, and that no one ball passes through any one lapping groove more than once un der ordinary conditions. i

The construction of the transfer mechanism is shown generally in Figs. 3, 4, and 5 of the drawings and in a diagrammatic arrangement in Figs. 6 and 7. This construction includes the transfer plates 29 and 30, which may be attached to the opposite faces of the disc 20 in any preferred manner, and an intermediate transfer member 50 having the plate members 51 provided with perforations 52 which have a supporting engagement with the ends of the flexible metallic ball-conveying tubes 58. .The plates 29 and30 are provided with series of obliquelyarranged passages through which the balls are transferred from the grooves on one face of the lapping member. through the corre-v sponding passages of the intermediate transfer member and to the corresponding opposltely-dlsposed grooves on the other face, and then to the next outer grooves 011 the first-mentioned face, and so on to the feeds tube 28. I preferably cause the balls to traverse each pair of oppositely disposed grooves in succession from the innermostfto the outermost pair of grooves in the series, and I have achieved this in the manner most clearly indicated in the diagrammatic views constituting Figs. 6 and 7 of the drawings.

In operation,as the balls are fed into any given lapping device through the passage 62 to the transfer member 50, they are-diverted through a Wall of the transfer member 50 to the entrance'end 31 of a passage inthe transfer plate 29 leading to groove member 1 which is the innermost of the series of concentric grooves on the corresponding side of the stationary lapping member. The course of the balls is now through the groove 1, indicated mainly by dotted lines in Fig. 6, until an outlet passage through the plate 29 is reached having an exit 82 from which the balls are conveyed through passage 33 across the space, greatly exaggerated and distorted in Fig. 6 for the sake of clearness, to the entrance end 34 of a passage leading through transfer plate 30 to the other face of the lapping member and to groove mem her 1 in that plate, oppositely disposed with relation to the first groove referred to. This groove having been traversed, the balls emerge at 85 and enter the passage 36 through which they pass to the other transfer plate 29, but it is to be noted that in the passage of the balls fromplate 30 toplate 29,that is, from the right hand to the lefthand face of the lapping member,--theballs do not pass to the oppositely-disposed groove member 1, which has already been traversed, but instead travel to the entrance 37 of. a passage leading to the second or neXt outer groove 011 the plate 29. Having traversed groove number 2, in turn, the balls emerge at 38 and travel through passage 39 to the entrance 4:0 of the oppositely-disposed groove number 2 on plate 30. lVhen this groove has been traversed, the balls emerge at 41 and travel through passage 42 to groove number 3 of plate 29.

Thus, it will be seen that the balls pass in alternation from one to the other side of thefixed lapping member and that, in passing in one direction through thetransfer plates the balls invariably move from one to the oppositelydisposed member of a pair of grooves; and that in passing through the transfer plates in the opposite direction, the balls invariably move outwardlyto the first groove of the next outer pair. This operation is continued, as has already been indicated, until each successive concentric pair of grooves from the innermost to the outermost has been traversed.

In order to prevent the production of an end thrust in the main drive-shaft 5, and thus eliminate the need for'making useof thrust bearings, I preferably mount the se ries of lapping members between a thrust collar d3, rigidly secured to the main driveshaft 5, and a pressureregulating nut or follower n having threaded engagement with the threaded portion 4&5 ofthe drive-shaft 5. It will be seen that, by turning the follower 44:, any required degreeof lateral pressure can be applied to the lapping members through the spring t6, and that the pressure thus produced is offset by the thrust collar 43,-with the result that the end thrust forces exerted on the drive-shaft 5 are mutually balanced and that no end thrust is exerted on the shaft bearings by the driveshaft as a whole. The freedom which the lapping members have of movement along the shaft 5 permit of their being forced into any desired compressing engagement with the interposed balls in the. grooves 9.

In order to bring about the most efi'ective engagement of the lapping grooves with the balls, I preferably form the grooves on sub stantially the same or on slightly larger radius of curvature than that of the balls themselves, so that the entire surface of the balls is acted upon by the attritious material carried in the opposing grooves. I preferably still further increase the effective area that is acted upon by the lapping grooves by. cutting the grooves in each plate to such a depth that the ribs or partitions separating adjacent grooves make contact with the opposing ribs on thecontiguous plate. I have discovered that, by properly proportioningthe width of the contacting faces of the ribs, they will be worn down somewhat more freely than the corresponding rate of wear of the lapping grooves, so as to insure that the ballsand coacting groove surfaces will be subjected to a suitable operating pressure. This provision for a faster rate of wear onthe faces ofthe partitions. than on the ball-engaging surfaces of the grooves not only has theadditional useful function ojt'providgingfor the ready access of. the abrasive-charged liquidto the lapping grooves and-the balls undergoing a the lapping operation therein, but it also avoids the need for occasionally removing and refacing the plates, as would otherwise be necessary.

In order toapply the abrasive agent in a regular and effective manner, I have provided a vat or trough, as at 4:7, in which a supply of lapping material 48, such as emery and oil, can be placed,and into which. the lower portions of the lapping members e2;- tend. ,It will be very clear that, by this arrangement, I not only providefor acontinual desirable agitation and stirring of the material 48 bythe rotation of the rotatable lapping members therein, but a very regular and uniform application of the liquid to the various lapping groovesis effected.

Because of the desirability of relieving the main drive-shaft5 ofthe entire weight of the lapping members, as well as. to prevent wear on the shaft, I preferably form the stationary plate carrying discs 20 witha greater diameter than that of the corresponding rotatable members and provide longitudinal ribs 49 on the inner surface of the vat 47, which peripherally engage-the discs 20 and serve as supports therefor, thus taking that much weight off the maindriveshaft 5 and relieving the shaft of wear in a corresponding degree. i

The various grooved lapping plates 1, 2, 3,and 4 are preferably forme in sections, as is indicated in. Fig. "3 of the drawings, and are clamped intoplace-on the faces of the supporting members by means of the holding members 50 which, by means of the screws 51, clamp the plates against the shoulders 52 formed l on each plate-carrying member near the central portion thereof.

It will be seen that the operation of the ball-lapping device described is continuous and that the balls, when they have traversed any given groove in the stationary plate under the impelling action of the contiguous rotating plate, are automatically transferred to the next groove in theseries and are also transferred from one set of grinding members to the next when the balls have traversed in succession all the grooves in a set, so that, under normal operating conditions, the balls are mechanically transferred from groove to groove and from lapping unit to lapping unit in succession and without any interruption of the lapping operation.

What I claim is-- 1. A ball-lapping machine comprising: a plurality of sets of relatively-rotatable members having lapping grooves along which the balls are impelled by the relative rotation of said members, means for transferring the balls from groove to groove ineach set, and means for transferring the balls from one set of relatively-rotatable members to another.

2. A ball-lapping machine comprising: a plurality of lapping units through which the balls are passed in a lapping operation, means for transferring the balls from one lapping unit to another as the passage of the balls through each unit is completed, and means whereby the number of lapping units employed may be increased or diminished to suit the requirements of the work.

3. A ball-lapping machine comprising: a plurality of sets of relatively-rotatable members having lapping grooves along Which the balls are impelled by the relative rotation of said members, means for automatically transferring the balls from groove to groove in each set in succession, and means for automatically transferring the balls to another set of relatively-rotatable membersupon the completion of travel of the balls through the grooves of one of the sets.

4. A ball-lapping machine comprising: a plurality of sets of relatively-rotatable members having lapping grooves along which the balls are impelled by the relative rotation of said members, means for transferring the balls from groove to groove in each set, means for transferring the balls from one set of relatively-rotatable members to another, and means whereby the number of sets of lapping members employed may be increased or diminished to suit the requirements of the work.

5. A ball-lapping machine comprising; a plurality of sets of relatively-rotatable memers having lapping grooves along which the balls are impelled by the relative rotation of said members, means for automatically transferring the balls from groove to groove 1n each set in succession and ina certain order, means for automatically transferring the balls to another set of relatively-rotatable members upon the completion of travel of the balls through the grooves of one set, and means for holding a mass of liquid abrasive material in such relation to the rotatable members that the members are partially immersed therein, whereby the rotation of said members stirs the material and applies it to the lapping grooves.

6. A ball-lappingmachine comprising: relatively-rotatable members mounted on a horizontal axis grooves along which the balls are impelled by the relative rotation of said members, and a container for abrasive material on which said members are mounted in such manner that the lower portions of said members are immersed in said material, whereby the operation of said members stirs the material and applies it to the lapping grooves.

7. A ball-lapping machine comprising: relatively-rotatable members having lapping grooves along which the balls are impelled by the relative rotation of said members, the successive grooves traversed by the balls being formed witha progressive decrease'in size, whereby a constant size relation is maintained between the balls and the lapping grooves. v

8. A ball-lapping machine comprising: relatively-rotatable members having lapping grooves along which the balls are impelled by the relative rotation of said members, means for automatically transferring the balls from groove to groove in succession and in a certain order, and said. successive grooves being formed with a progressive decrease in size, whereby a con and having lapping stant size, relation is maintained between size, whereby a constant size relation is maintained between 'theballs and the lapping grooves as the balls travel through.

the machine and each groove invariably operates on balls of substantially the same size. 1

10. A ball-lapping machine, comprising: of setsof relatively-rotatable a pluralit members having lapping grooves along Whichthe balls are impelled by the relative the lapping of the balls in a single journey through the machine, whereby each lapping groove acts on balls of substantially the same s ze.

11. A ball-lapping machine comprising: relatively-rotatabl members having lapping grooves along which the ballsare impelled by the relative rotation of said members, said lapping grooves being separated by partition Walls Whose width is suchthat the rate of wear on the faces of said partition walls is greater than the Wear on the surfaces of the grooves, whereby an effective operating pressure and size relatlon be tween the balls and the grooves is constantly maintained. a Q

12. A ball-lapping machine comprising: relatively-rotatable lapping members, a horizontal shaft on which said members are mounted, said members being mounted to be movedlongitudinally of said axis, a collar adjustably mounted on said shaft for pressing said members into close operating relation, and a collar rigidlysecured to said shaft and'serving as an abutment member against Which said lapping members are pressed, vvherebythe bearings in which said shaft is journaled are relieved of end thrust, said lapping members being removably mounted on the shaft to provide for varying the number of members used.

13. A ball-lapping machine comprising: relatively-rotatable lapping members, a horizontal shaft on Which said members are mounted, said members being mounted to" be moved longitudinally of said shaft, a

collar having threaded engagement With said shaft for pressing said members into effective operative relation, a spring interposed between said collar and said lapping members, a collar rigidly secured to said shaft and serving as an abutment member against which said lapping members are pressed, whereby the bearings in which said shaft is mounted are relieved of end thrust, and said lapping members being individually removable at will from said shaft to vary the number of membersused, said shaft being threaded for a substantial part of its length to adjust the position of the movable collar to the number of members used. v

14:. p A ball-lapping device comprising: a

lapping'member having oppositely-disposed H faces with lapping grooves formed in said faces, means for impelling balls alongsaid grooves to perform the lapping operation, and means for transferring the balls from a groove in one face of the lapping member to a groove in the opposite face in alternation as the travel of the ballsthrough each individual groove iscompleted.

15. A ball-lapping device comprising a lapping member having oppositely-disposed faces with concentrically-arranged lapping grooves formed in said faces, means for impelling balls along said grooves to perform thelapping operation, and means for trans ferring the balls from a groove in one face of the lapping member to a groovein the opposite face in alternation and in succession from the innermost t0 the outermost groove, as the travel of the balls through the individual grooves is completed, 7

16. A ball-lapping device comprising: a lapping plate having oppositely-disposed lapping faces, lappingplates"arranged in cooperative relation With said faces, concentric ball-lapping grooves formed in the contiguous faces of said plates, means for relatively rotating said plates to impel the balls through said grooves, and means for transferring the balls from a groove in one face of the intermediate lapping plate through said plate to a groove in the opposite'face thereof in alternation and in succession from the innermost to the outermost groove as the travel of the balls through the individual grooves is completed. I

17. A ball-lapping device comprising: a lapping. plate having o )positely-disposed lapping faces, lapping plates arranged in cooperative relationivith said faces, concentric ball-lapping grooves formed in oppositely-disposed pairs in the contiguous faces of Said plates, meansfor relatively rotating said plates to impel the balls through said grooves, and means for transferring the balls from a groovein one face of'the intermediate lapping member to the oppositely-disposed groove of the pair and from the second groove of the pair to the opposite face of the intermediate lapping member and the first groove of the next outer pair of grooves.

18. A balLlapping machine comprising: a stationary lapping member, a rotatable'lapping member arranged to rotate substan tially in contact With said stationary member, a plurality of concentric grooves in the contacting surface of one of sald members so arranged that balls placed in said grooves will be caused to travel therein by the rotation of said rotatable member, and transfer passages in said stationary lapping-member for transferring the balls from one to another of said concentric grooves when the travel of the balls about the path of travel afforded by each groove has been substantially completed. i

19. A ball-lapping machine comprising: a stationary lapping member having oppositely-disposed lapping surfaces, rotatable lapping members arranged to rotate substantially in contact with the oppositely-disposed lapping surfaces of the interposed stationary lapping member, a plurality of annular grooves in each set of contacting surfaces so arranged that balls placed in said grooves will be caused to travel therein by the rotation of said rotatable members, and transfer passages in said stationary member for transferring the balls from a groove in one set of contact surfaces to a groove in the other set when the travel of the balls about the path of travel afforded by the first-named groove has been substantially completed,

20. A ball-lapping machine comprising: a'stationary lapping member having oppositely-disposed lapping surfaces, rotatable lapping members arranged to rotate substantially in contact with the oppositely-disposed lapping surfaces of the interposed stationary lapping member, a plurality of concentric grooves in each set of contacting surfaces with a groove in each set oppositely disposed with relation to a corresponding groove in the other set, said grooves being so arranged that balls placed therein will be caused to travel in said grooves by the rotation of said rotatable members, and transfer passages in said stationary member for transferring the balls from a groove in one set of contact surfaces to the oppositelydisposed groove in the other set when the travel of the balls about the path of travel afforded by the first-named groove has been substantially completed.

21. A ball-lapping machine comprising: a stationary lappingmember having oppositely-disposed lapping surfaces, rotatable lapping members arranged to rotate substantially in contact with the oppositely-disposed lapping surfaces of the interposed stationary lapping member, a plurality of concentric grooves in each set of contacting surfaces with a groove in each set oppositely disposed with relation to a corresponding groove in the other set, said grooves being so arranged that balls placed therein will be caused to travel in said grooves by the rotation of said rotatable members, transfer passages in said stationary member for transferring the balls from a groove in one set of contact surfaces to the oppositelydisposed groove in the other set when the travel of the balls about through the first named groove has been completed, and other transfer passages in said stationary mem ber for re-transferring the balls from the second-named groove to a groove in the first-named set radially removed from the first-named groove.

22. A ball-lapping machine comprising:

' a plurality of sets of lapping devices, each set consisting of a stationary lapping mem her having oppositely-disposed lapping surraces, rotatable lapping members arranged to rotate substantially in contact with the oppositely-disposed lapping surfaces ofthe interposed stationary lapping member, a plurality of annular grooves in each set of contact surfaces, transfer passages in said stationary member for transferring balls successively from one to another of said grooves until allthe grooves have been traversed by the balls, means for feeding balls to the first set of lapping devices, and means for automatically conveying balls from one to another set of lapping devices as the balls complete their travel through the series of grooves in each set, whereby the lapping operation is rendered continuous.

23. A ball-lapping machine comprising: a substantially disc-shaped stationary lapping member having oppositely-disposed lapping surfaces, substantially disc-shaped rotatable lapping members arranged to rotate substantially in contact with the oppositely-disposed lapping surfaces of the interposed stationary lapping member, said lapping members being mounted on a horizontal axis, a container for abrasive material into which the lower portions of said lapping members extend, a plurality of annular grooves in each set of contact surfaces, and transfer passages in said stationary member for transferring balls successively from one to another of said grooves.

24. A ball-lapping machine comprising: a plurality of sets of lapping devices, each set consisting of a substantially disc-shaped stationary lapping member having oppositely-disposed. lapping surfaces, substantially disc-shaped rotatable lapping members arranged to rotate substantially in contact with the oppositely-disposed lapping surfaces of the interposed stationary lap ping members, said lapping members being mounted on a horizontal axis, a container for abrasive material into which the lower portions of said lapping members extend, a plurality of annular grooves in each set of contact surfaces, transfer passages in each stationary member for transferring balls successively from one to another of said grooves until all the grooves have been traversed by'the balls, means including a spring for pressing the lapping members into effective ball-lapping relation, means for continuously feeding balls to the first set of the plurality of lapping devices, and means for automatically conveying the balls from one lapping set to another as the balls complete their travel through the series of grooves in each set, whereby the operation of lapping the balls is rendered continuous.

Y ALBERT F. ROCKW ELL. 

